The present invention involves a process for coating a substrate, in particular for manufacturing a sensor, wherein on a portion of the surface of the substrate, at least one texture is created on which a layer that is to be applied on the surface of the substrate, adheres better than on a surface area of the substrate located outside of the texture, wherein the layer is applied after creating the texture on the surface of the substrate and areas of the layer which overhang laterally beyond the texture are removed mechanically, and wherein the material of the texture contains at least one chemical element or a chemical compound, which the layer applied on the texture does not have or has only in a smaller concentration than the material of the texture.
From German published patent application DE 196 41 777 A1, it is already known to use such a process for the manufacture of a sensor with a metal electrode in a MOS-arrangement. This process has thus proven itself to be advantageous in practice, since it makes possible a textured coating of a substrate, without the coating applied to the substrate having to be textured for this using a photolithographic process and/or an etching process. A contamination of the manufacturing facilities used for the MOS semiconductor manufacture by the metallic electrode material to be applied to the substrate is thus avoided. A contamination of this sort can occur, for example, in photolithographic texturing processes when stripping the photoresist or when etching the metallic layer to be textured. Metallic contaminations of the manufacturing facilities are therefore especially undesirable, since they reduce the puncture resistance of gate oxides and thus reduce the reliability of the semiconductors manufactured with the manufacturing facilities.
A disadvantage of the previously known coating process consists, however, in that the layer may only be applied with a relatively small thickness, since the areas of the layer overhanging laterally beyond the texture can otherwise not be removed by mechanical mechanisms. The layers manufactured according to the process mentioned at the beginning therefore have only a comparatively small resistance to temperature, that is, the chemical compounds or elements located in the textured area of the substrate, such as silicon, can diffuse out of the substrate into the layer that is applied onto it, and possibly reach the surface of this layer. In the process, it is even possible that the substances diffused out of the substrate into the layer enter into a chemical bond with the materials contained in the layer and/or mix with them and change their chemical and/or physical properties, for example the resistance to corrosion. Such an undesired diffusion of materials out of the substrate into the layer applied on it occurs especially at higher temperatures, for example above 100.degree. C. Such temperatures are, however, unavoidable in the manufacture of semiconductors and can, for example, occur during a temperature treatment for curing (hardening) on a lacquer coat located on the substrate or when applying a bonding compound on the substrate.